Medically speaking, the biblical disease that is usually translated as “leprosy” (tsara’at) has nothing to do with slander (motsi shem ra). But our pre-scientific rabbinic ancestors connected the two as if they did. Tsara’at for them was like advanced and untreatable cancer for us. They deliberately associated the gravest threat to bodily health with character damage caused by the misuse of language, as if to say they were equivalent.

That decision should take our breath away. Our culture cares relatively little about damage we do through verbal abuse. Beyond taking adequate care to avoid lawsuits, we engage rather freely in speaking loosely of others.

Jewish law, by contrast, is nothing short of obsessive on the subject. It delineates three kinds of verbal abuse and insists that we cease and desist from each and every one: 1. We are forbidden to invent or pass on lies about people (motsi shem ra). 2. We may not even speak negatively about people regarding things that happen to be true (lashon hara)! 3. And even idle gossip (r‘chilut) is forbidden, since gossip thrives on the objectionable, if not the downright sordid.

Clear distinctions among the three categories emerge only in the Middle Ages, where, for instance, the two great legalists Maimonides and Nachmanides argue whether lashon hara is its own classification or just a particularly heinous case of r’chilut. Until then, rabbinic writing frequently lumps them all together as just plain scurrilous talk, which insidiously eats away at a person’s good name and thereby causes injury. The Talmud goes so far as to say that “speaking lashon hara is like denying the existence of God.”

This, mind you, is for lashon hara — speaking evil of others, even if the charges are true! Why is even this lesser offense equivalent to, of all things, apostasy — pretty much the worst crime against God that the Jewish imagination can muster?

Our commentators are of no single opinion on the subject. One prominent example (attributed to Maimonides himself, among others) provides the slippery slope scenario. If we get used to speaking negatively about our own ordinary friends and acquaintances, it is only a matter of time until we do so even of people in authority, including those whose wisdom and way of life testify of God’s existence. We would thereby end up implicitly casting doubt on the most obvious human exemplars of God’s reality.

A better answer, I think, comes from a teaching attributed to the Chafetz Chaim, who is said to have cautioned against speaking lashon hara even of oneself. Discussion of lashon hara usually assumes that the prohibition is rooted in the damage that it causes. But what damage do we cause ourselves by owning up to our own negative character traits? Doesn’t Judaism demand we do just that? We call it teshuvah (“repentance”)!

The Chafetz Chaim is, no doubt, thinking of people who go beyond proper teshuvah — people, that is, who habitually run themselves down. It is this constant negativity toward oneself that is forbidden — because being overly self-critical is a slight on God, the Creator who made us.

At stake is what we call religious anthropology, our doctrine of human nature. Judaism insists on seeing something Divine in each and every one of us. In 1994, a singing group, “The Halo Benders,” released an album entitled, “God Don’t Make No Junk” — a title that has inspired hundreds of T-shirts, bumper stickers, website postings, and other forms of subtle protest against a society that teaches us that we are, overall, wanting.

We can understand the Chafetz Chaim as emphasizing the much earlier and specifically Jewish version of “God don’t make no junk.” It’s one thing to take honest stock of who we are; it’s quite another to run ourselves down all the time (even if the charges are mostly true) without simultaneously appreciating what is good, decent and even godly within us. The self-directed lashon hara of speaking overly negatively about ourselves ignores the reality of God that forms the essence of every living soul.

The implicit denial of God’s presence in any human being, even ourselves, is indeed the subtlest of apostasies. And it is a sin.

Rabbi Lawrence A. Hoffman is professor of liturgy, worship and ritual at Hebrew Union College in New York. He is the author of “We Have Sinned: Sin and Confession in Judaism (Jewish Lights Press).”